Studies in sesquiterpenes.

Abstract

The thesis “Studies in Sesquiterpenes” is divided into three parts:

Part I A brief account of the chemistry of naturally occurring cadinenes, cadinols, and related compounds possessing the cadinane skeleton has been given. The stereochemistry and absolute configuration of the cadinenic sesquiterpenes and the biogenesis of sesquiterpenes in general are discussed.

Part II This part comprises the total synthesis of (+)-4-isopropyl-decalin-1,6-dione, starting from 6-methoxy-4-isopropyl-tetralone-1. Lithium-in-amine reduction of 6-methoxy-4-isopropyl-tetralone-1 and 6-hydroxy-4-isopropyl-tetralone-1, with a view to obtaining larger quantities of the aforementioned diketone, has met with little success. The synthesis of (+)-cadinene dihydrochloride, utilising (+)-4-isopropyl-decalin-1,6-dione, is also described.

Part III The results of dehydrohalogenation of (-)-cadinene dihydrochloride to obtain ?-cadinene have been presented. The hydrogenation of 6-hydroxy-4-isopropyl-tetralone-1 with a number of catalysts to obtain 4-isopropyl-decalin-1,6-diol, suitable for conversion to (+)-4-isopropyl-decalin-1,6-dione, has been explored. Compounds such as 1,2,3,4-tetrahydro-1-isopropyl-7-hydroxy-naphthalenone, 1-isopropyl-7-hydroxy-decalin, and 4-isopropyl-decalin-1,6-diol were obtained in the above hydrogenation experiments and have been fully characterised.